This invention relates to compositions for oil treating generally classified in U.S. Patent Office Class 252, subclass 8.55, and to Chemistry of the Carbon Compounds, sulfonation products of aromatic mixtures classified in Class 260, subclass 505.
Petroleum sulfonates have been prepared by a variety of means, for example, sulfonated with sulfur dioxide (U.S. Pat. No. 2,999,812), sulfur dioxide and chlorine (U.S. Pat. No. 2,197,800), oleum (U.S. Pat. No. 2,845,455), and sulfur trioxide (U.S. Pat. No. 3,183,183). U.S. Pat. Nos. 3,215,628 and 2,815,370 teach the use of specific hydrocarbon fractions. Other patents of lesser interest include U.S. Pat. Nos. 2,174,508, 2,800,962; 3,173,864; 3,308,068; 3,244,622; and 3,418,239.
The prior art suggests that whole crude oil can be sulfonated and used in oil production. (See U.S. Pat. Nos. 1,822,271; 3,126,952; and 3,302,713 teaching the use of whole crude sulfonates in secondary-type oil recovery and U.S. Pat. Nos. 2,798,851; 2,953,525; and 3,198,832 teaching use of such sulfonates in drilling muds.) However, we are unaware of a teaching as to how this can be done or any commercial use of such a process. Specific teachings of which we are aware require the removal of the light and/or heavy ends and the use of only the middle cuts to manufacture the petroleum sulfonates.
There are a number of reasons for fractionating crudes prior to sulfonation. Inter alia, it is difficult to obtain a marketable product from asphaltenes which tend to form tarry materials which foul reactors and sometimes form coke-like deposits. Also, the light ends are often aliphatics or light aromatics which will not produce the desired product.
We have now discovered that commercially acceptable sulfonates can be prepared from a variety of crude oils using our processes. While we were surprised to be able to prepare sulfonates in good yields and without coking or the formation of tarry products, we were pleased when we found that the sulfonates produced form economic micellar systems suitable for use in oil recovery.
The upcoming "energy crisis" puts our invention in context. T. M. Geffen (Oil & Gas Journal, May 7, 1973, pp. 66-76) indicates that 55 billion barrels of additional crude can be recovered via tertiary recovery. Heretofore, tertiary recovery processes (see U.S. Pat. Nos. 3,254,714; 3,307,628; 3,504,744; 3,261,399; 3,497,006; 3,506,070; 3,354,953; 3,330,344 and 3,348,611--most using petroleum sulfonate surfactants) have all proved uneconomic because, inter alia, the cost of materials used made the processes uneconomic and the amounts of oil recovered were too small. Our process provides sulfonates at a price sufficiently low to aid substantially in the commercialization of tertiary oil recovery using secondary-type oil recovery techniques taught in the above listed patents assigned to Marathon Oil Company.
This "tertiary" oil is a resource which will not create balance of payments problems and which cannot be withheld by foreign governments and our process should be considered within this context.